Author
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CHARLET, LAURENCE |
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BREWER, GARY - NDSU |
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Submitted to: Proceedings Sunflower Research Workshop
Publication Type: Proceedings Publication Acceptance Date: 1/30/1998 Publication Date: N/A Citation: N/A Interpretive Summary: The states of North Dakota, South Dakota, and Minnesota comprise the major U.S. sunflower producing region. Insects, including the sunflower midge are one of the factors limiting sunflower production. The larvae cause altered growth of the sunflower heads which results in few if any seeds. The incidence of sunflower midge damage has been increasing. Currently, no controls are available. Two factors probably enhance the high midge populations seen in the last several years: a large spring emergence of the overwintering population and readily available hosts. Past control efforts looked at insecticides, planting dates, and genetic resistance. None of those control efforts gave consistent and adequate results. Tests were done in 1997 to determine larval susceptibility to a number of insecticides. Larval mortality was high with all the insecticides tested. The sunflower midge passed through several generations in 1997. The overwintering generation adults began emerging in late June and peaked on 13 July and again on 18 July. First generation adults began emerging on 13 August and peaked on 24 August. These adults produce second generation eggs. Overwintering larvae are most likely a mixture of first and second generation larvae. There was no apparent correlation of accumulated rainfall or soil moisture conditions with emergence. Projects are currently being developed to study midge biology and adult emergence, biological control, host-plant resistance, insecticide screening and treatment methodology, and cost/benefit ratios for midge treatment. Increased knowledge about the midge and different IPM strategies is needed to offer the greatest potential for successfully managing this cryptic pest to reduce future damage. Technical Abstract: The states of North Dakota, South Dakota, and Minnesota comprise the major U.S. sunflower producing region. Insects, including the sunflower midge, Contarinia schulzi, are one of the factors limiting sunflower production. The larvae cause altered growth of the sunflower heads which results in few if any seeds. The incidence of sunflower midge damage has been increasing. Currently, no controls are available. Two factors probably enhance the high midge populations seen in the last several years: a large spring emergence of the overwintering population and readily available hosts. Past control efforts looked at insecticides, planting dates, and genetic resistance. None of those control efforts gave consistent and adequate results. Tests were done in 1997 to determine larval susceptibility to a number of insecticides. Larval mortality was high with all the insecticides tested. The sunflower midge passed through several generations in 1997. The overwintering generation adults began emerging in late June and peaked on 13 July and again on 18 July. First generation adults began emerging on 13 August and peaked on 24 August. These adults produce second generation eggs. Overwintering larvae are most likely a mixture of first and second generation larvae. There was no apparent correlation of accumulated rainfall or soil moisture conditions with emergence. Projects are currently being developed to study midge biology and adult emergence, biological control, host-plant resistance, insecticide screening and treatment methodology, and cost/benefit ratios for midge treatment. Increased knowledge about the midge and different IPM strategies is needed to offer the greatest potential for successfully managing this cryptic pest to reduce future damage. |
